JP4583121B2 - Glass ceramic substrate - Google Patents

Description

  The present invention provides a ferrite layer for increasing an inductance value, which is formed by firing together with a glass ceramic insulating layer and having a coil conductor embedded therein, in an insulating base made of a glass ceramic sintered body. The obtained glass ceramic substrate.

  2. Description of the Related Art Conventionally, many electronic devices are incorporated in electronic devices such as mobile communication devices such as mobile phones. Such communication devices such as mobile phones have been rapidly reduced in size in recent years, and various electronic devices mounted thereon are required to be reduced in size and thickness. For example, an LC filter having a configuration in which a coil is built in a glass ceramic substrate is known. In the case of this LC filter, it has the advantage that it can be reduced in size and thickness by incorporating the coil of the chip component in the inside of the glass ceramic substrate. Among them, a coil having a large inductance exceeding 100 nH is relatively large as a chip component, and incorporating this in a glass ceramic substrate has an advantage that the effect of miniaturization and thinning is great.

  However, in a glass ceramic substrate with a built-in coil, the coil is formed in a non-magnetic glass ceramic substrate. Therefore, in order to incorporate a coil capable of obtaining a relatively large inductance of about 100 nH, the number of turns of the coil must be increased. Therefore, even if the coil is built in the glass ceramic substrate, there is a problem that it becomes impossible to achieve a reduction in size and thickness.

  Therefore, in recent years, a ferrite layer having ferromagnetism is formed inside a glass ceramic substrate, and the coil is embedded in this ferrite layer, so that a coil exceeding 100 nH can be built in without increasing the number of turns of the coil, thereby increasing the surface. The mounting process is simplified and the glass ceramic substrate is downsized.

In such a method, the ferrite layer and the glass ceramic insulating layer are co-fired in order to firmly join the ferrite layer and the glass ceramic insulating layer by diffusing the glass of the glass ceramic insulating layer into the ferrite layer. A ferrite layer is formed inside the glass ceramic substrate.
JP-A-6-20839 JP-A-6-21264

However, in a conventional glass ceramic substrate in which a ferrite layer is formed inside the glass ceramic substrate as described above, and a coil is embedded in the ferrite layer, the ferrite layer glass is formed in the simultaneous firing of the ferrite layer and the glass ceramic insulating layer. By bonding with the glass of the glass ceramic substrate, the ferrite layer is restrained by the glass ceramic insulating layer and contracting, and the ferrite layer is insufficiently sintered and roughened. As a result, to enter such atmospheric moisture immersion of a ferrite layer exposed to the glass-ceramic substrate side, there is a problem that water is generated in the glass ceramic substrate. When water absorption occurs in the glass ceramic substrate, an electrical characteristic failure such as a short circuit of the wiring conductor formed in the inner layer of the glass ceramic substrate is induced, and the electrical reliability of the glass ceramic substrate is lowered.

On the other hand, in a conventional glass ceramic substrate in which a ferrite layer is formed inside the glass ceramic substrate as described above, and a coil is embedded in the ferrite layer, the internal ferrite layer has a small volume or low density for the following reasons. It is difficult to stably obtain a glass ceramic substrate having sufficient coil characteristics by using a ferrite layer, because there is variation in coil inductance between glass ceramic substrates manufactured in the same manner. There was a problem that there was. For example, it was not possible to obtain a glass ceramic substrate having a sintered density of 5.0 g / cm ³ or higher at a firing temperature of 800 to 1000 ° C. and a ferrite layer having a permeability of 100 or higher in a frequency band of 1 KHz to 10 MHz.

Further, in the conventional configuration, in order to fire a ferrite layer having a firing temperature exceeding 1000 ° C. at 800 ° C. to 1000 ° C. which is the firing temperature of the glass ceramic substrate, sintering of glass powder, SiO ₂ , Al ₂ O ₃ or the like. Auxiliary had to be added. In general, the magnetic properties of a magnetic material such as ferrite are expressed using magnetic permeability (μ) as an index. The higher the magnetic permeability, the higher the coil inductance. However, if there is a nonmagnetic part in the magnetic material, the magnetic permeability decreases in proportion to the cube of the volume of the nonmagnetic part. Therefore, when glass powder or sintering aid, which is a non-magnetic material, is added to the ferrite layer, these form a non-magnetic region in the ferrite layer, reducing the ferrite density in the ferrite layer, and increasing the permeability. There was a problem that became low.

  Furthermore, since the thermal expansion coefficient of the ferrite layer and the thermal expansion coefficient of the glass ceramic insulating layer are different in the simultaneous firing of the ferrite layer and the glass ceramic insulating layer, magnetostriction occurs due to stress applied to the ferrite layer during the simultaneous firing process. However, there is also a problem that it is difficult to obtain a desired magnetic permeability because the magnetic permeability of the ferrite layer is lowered.

  In addition, if the ferrite layer is formed thick in order to obtain sufficient inductance, the fired ferrite layer tends to peel off due to the stress generated due to the difference in thermal expansion coefficient between the glass ceramic substrate and the ferrite layer. There was also.

  The present invention has been made in view of the above-described problems in the prior art, and an object of the present invention is that it can be fired at a low temperature simultaneously with the glass ceramic insulating layer, has no water absorption from the end face, and has a high frequency band. An object of the present invention is to provide a glass ceramic substrate having a ferrite layer having a high magnetic permeability and having a high and stable inductance of a coil conductor incorporated in the ferrite layer.

In the glass ceramic substrate of the present invention, a ferrite layer having the same size as the glass ceramic insulating layer is formed on an inner layer of an insulating substrate formed by laminating a plurality of glass ceramic insulating layers made of glass and filler, with an intervening layer interposed. A glass ceramic substrate in which a coil conductor is embedded in the ferrite layer , and the end of the intervening layer is exposed from the exposed portion of the ferrite layer on the side surface of the glass ceramic substrate. A water-impermeable protective layer is formed over the portion where the portion is exposed .

The glass ceramic substrate of the invention preferably the protective _layer, SiO 2 _-B 2 _{O 3} based _{glass, SiO 2 -B 2 O 3 -Al} 2 O 3 based _glass, SiO 2 _-Al 2 _{O 3 system,} PbO characterized in that it consists -SiO ₂ -B ₂ O ₃ based _{glass, Bi 2 O 3 -SiO 2 -B} 2 at least one of _{O 3} based glass and _ZnO-SiO 2 _-B 2 _{O 3} based glass .

  The glass-ceramic substrate of the present invention is preferably characterized in that the protective layer is made of the same glass as the glass-ceramic insulating layer and glass-ceramic made of the filler.

  In the glass-ceramic substrate of the present invention, preferably, the protective layer is made of at least one resin selected from an epoxy resin, an acrylic resin, a silicon resin, and a fluorine resin.

In the glass ceramic substrate of the present invention, preferably, the ferrite layer comprises 63 to 73 wt% of Fe ₂ O ₃ , 5 to 10 wt% of CuO, 5 to 12 wt% of NiO, and 10 to 23 wt% of ZnO. % Content.

The glass ceramic substrate of the present invention preferably prior Symbol intervening layer, and the thermal expansion coefficient of the ferrite layer and the thermal expansion coefficient of the glass-ceramic insulating layers with contains the same ingredients as the glass and the ferrite layer It is characterized by comprising an insulating layer having a thermal expansion coefficient between.

The glass ceramic substrate of the present invention preferably prior Symbol intervening layer, Cu, Ag, Au, Pt, contain at least one metal and glass of the Ag-Pd alloy and Ag-Pt alloy It is characterized by comprising a sintered metal layer.

  In the glass ceramic substrate of the present invention, preferably, the intervening layer contains the same components as glass and the ferrite layer, and the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer are An insulating layer having a thermal expansion coefficient between, and a sintered metal layer containing at least one metal of Cu, Ag, Au, Pt, an Ag—Pd alloy, and an Ag—Pt alloy and glass. It is characterized by being laminated.

  In the glass ceramic substrate of the present invention, preferably, the intervening layer contains the same components as glass and the ferrite layer, and the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer are An insulating layer having a thermal expansion coefficient between, and a sintered metal layer containing at least one metal of Cu, Ag, Au, Pt, an Ag—Pd alloy, and an Ag—Pt alloy and glass. It is characterized by being formed so as to be arranged in the same layer.

According to the glass ceramic substrate of the present invention, from the site where the end of the ferrites layer side of the glass-ceramic substrate is exposed toward the site where the end portion of the intermediate layer is exposed, water-impermeable protective layer is formed since it was, it is possible to prevent the ferrites layer absorbs water, as a result, the electrical characteristics such as the wiring conductor formed on the inner layer of the glass-ceramic substrate is short-circuited failure does not occur.

In the glass ceramic substrate of the present invention, the protective layer is preferably made of SiO ₂ —B ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass, SiO ₂ —Al ₂ O ₃ glass _, PbO— SiO ₂ -B ₂ O ₃ based _glass, since consisting of Bi ₂ O ₃ -SiO _{2 -B 2} at least one of _{O 3} based glass and _ZnO-SiO 2 _-B 2 _{O 3} based glass, a protective layer Whether formed by firing at the same time as the glass ceramic substrate or when formed after firing the glass ceramic substrate, the protective layer can be firmly bonded. As a result, the protective layer does not peel off, and the glass ceramic substrate can be coated with good adhesion from at least the end where the ferrite layer is exposed to the end where the intervening layer is exposed. Water absorption of the substrate can be effectively prevented.

In the glass ceramic substrate of the present invention, the protective layer is preferably a glass ceramic made of the same glass and filler as the glass ceramic insulating layer, so that the protective layer has the same composition as the insulating base. Further, the sintering behavior is the same, and the exposed end portion of the ferrite layer can be covered with good adhesion from the end portion of the intervening layer, and water absorption of the glass ceramic substrate can be more effectively prevented.

In the glass-ceramic substrate of the present invention, preferably, the protective layer is made of at least one resin of epoxy resin, acrylic resin, silicon resin, and fluorine resin. A thermal load is not applied to the glass ceramic substrate, and the glass ceramic substrate is not broken by a stress due to a temperature difference. As a result, the protective layer can cover the glass ceramic substrate with good adhesion from the portion where the end of the ferrite layer on the side surface of the glass ceramic substrate is exposed to the portion where the end of the intervening layer is exposed. Water absorption can be effectively prevented.

In the glass ceramic substrate of the present invention, the ferrite layer preferably contains 63 to 73% by weight of Fe ₂ O ₃ , 5 to 10% by weight of CuO, 5 to 12% by weight of NiO, and 10 to 23% by weight of ZnO. Therefore, using NiCuZn ferrite, which is a combination of NiZn ferrite excellent in high frequency band characteristics and CuZn ferrite that can be sintered at low temperature, a ferrite layer with a coil embedded in the same size as the glass ceramic insulating layer Can be formed. As a result, the ferrite layer can be fired simultaneously with the glass ceramic substrate without adding a glass powder or a sintering aid such as SiO ₂ or Al ₂ O ₃ , and high permeability can be obtained in a high frequency band. And a glass ceramic substrate with a built-in coil having high inductance can be obtained.

The glass ceramic substrate of the present invention preferably via Zaiso the heat between the thermal expansion coefficient of the ferrite layer of the glass ceramic insulating layer with contains the same components as the glass and the ferrite layer Because it consists of an insulating layer with an expansion coefficient, the stress caused by the difference in thermal expansion between the ferrite layer and the glass ceramic insulating layer is relaxed by an insulating layer that is intermediate between the thermal expansion of the glass ceramic insulating layer and the thermal expansion of the ferrite layer. It is possible to suppress a decrease in magnetic permeability due to magnetostriction and firmly bond the ferrite layer and the glass ceramic insulating layer.

The glass ceramic substrate of the present invention preferably via Zaiso is, Cu, Ag, Au, Pt, contains at least one metal and glass of the Ag-Pd alloy and Ag-Pt alloy Because it consists of a sintered metal layer, the stress caused by the difference in thermal expansion coefficient between the ferrite layer and the glass ceramic insulating layer can be relaxed by plastic deformation of the sintered metal layer, and the decrease in permeability due to magnetostriction is suppressed. In addition, the ferrite layer and the glass ceramic insulating layer can be firmly bonded.

  In the glass ceramic substrate of the present invention, preferably, the intervening layer contains the same components as the glass and ferrite layer, and the thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer. An insulating layer having a coefficient and a sintered metal layer containing at least one metal of Cu, Ag, Au, Pt, Ag—Pd alloy and Ag—Pt alloy and glass are laminated. Therefore, the action of the insulating layer and the action of the sintered metal layer act synergistically to more effectively relieve the stress caused by the difference in thermal expansion between the ferrite layer and the glass ceramic insulating layer. Can do. As a result, a decrease in magnetic permeability due to magnetostriction can be further effectively suppressed, and the bonding between the ferrite layer and the glass ceramic insulating layer can be further strongly bonded.

  In the glass ceramic substrate of the present invention, preferably, the intervening layer contains the same components as the glass and ferrite layer, and the thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer. An insulating layer having a coefficient and a sintered metal layer containing glass and at least one metal of Cu, Ag, Au, Pt, Ag—Pd alloy and Ag—Pt alloy are in the same layer. Since the insulating layer and the sintered metal layer operate in the same layer, the stress caused by the difference in thermal expansion between the ferrite layer and the glass ceramic insulating layer is reduced. It can be more effectively relaxed. As a result, a decrease in magnetic permeability due to magnetostriction can be further effectively suppressed, and the bonding between the ferrite layer and the glass ceramic insulating layer can be further strongly bonded.

  The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of a glass ceramic substrate of the present invention, wherein 1 is an insulating base composed of a plurality of glass ceramic insulating layers 6, 2 is a ferrite layer, and 3 is a wiring conductor including a coil conductor. 4 is an insulating layer, 5 is a sintered metal layer, 6 is a glass ceramic insulating layer, and 7 is a protective layer.

  The insulating substrate 1 of the present invention is configured by laminating a plurality of glass ceramic insulating layers 6, and a ferrite layer 2 in which a wiring conductor 3 is embedded in an inner layer thereof is interposed via an insulating layer 4 and a sintered metal layer 5. Is formed.

  The insulating substrate 1 is made of a glass ceramic green sheet to be a glass ceramic insulating layer 6 and a ferrite green sheet to be a ferrite layer 2, and a conductive paste to be a wiring conductor 3 and an insulating layer to the glass ceramic green sheet and the ferrite green sheet. After the insulating paste to be 4 and the metal paste to be the sintered metal layer 5 are printed, a plurality of these glass ceramic green sheets and ferrite green sheets are laminated, and 800 to 1000 ° C. in air or in a humidified nitrogen atmosphere. It is made by firing at a temperature of

  The glass ceramic insulating layer 6 is obtained by first mixing glass powder and filler powder (ceramic powder), and further mixing an organic binder, plasticizer, organic solvent, etc. to obtain a slurry, from which a doctor blade method, a rolling method, a calender roll method, etc. Thus, a glass ceramic green sheet to be the glass ceramic insulating layer 6 is manufactured, and the ferrite layer 2 is sandwiched between a plurality of glass ceramic green sheets.

Examples of the glass powder include SiO ₂ —B ₂ O ₃ , SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ , SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO (where M is Ca , Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O—M ² O system (where M ¹ and M ² are the same or different, and Ca, Sr, Mg, Ba or Zn) _{shown), SiO 2 -B 2 O 3} -Al 2 O 3 -M 1 O-M 2 O system (where, ^{M 1} and ^{M 2} are the same as _{above), SiO 2 -B 2 O 3} -M ³ ₂ O system (where M ³ represents Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ³ ₂ O system (where M ³ is the same as above), Pb glass or Bi glass can be used.

Examples of the filler powder include Al ₂ O ₃ , SiO ₂ , a composite oxide of ZrO ₂ and an alkaline earth metal oxide, a composite oxide of TiO ₂ and an alkaline earth metal oxide, and Al ₂ O. A composite oxide (for example, spinel, mullite, cordierite) containing at least one selected from ₃ and SiO ₂ can be used.

  The wiring conductor 3 is formed on the surface and inside of the insulating substrate 1 and inside the ferrite layer 2, and is prepared by kneading a suitable organic binder and solvent into metal powder such as Cu, Ag, Au, and Ag alloy. The conductive paste is applied to the glass ceramic green sheet surface and the ferrite green sheet surface by a screen printing method, a gravure printing method, or the like, and fired simultaneously with the glass ceramic green sheet and the ferrite green sheet.

  The insulating layer 4 as an intervening layer is formed between the ferrite layer 2 covering the upper and lower surfaces of the wiring conductor 3 and the glass ceramic insulating layer 6, and the ferrite powder contained in the glass powder and the ferrite layer 2 An insulating paste prepared by kneading an appropriate organic binder and solvent is blended so that the thermal expansion coefficient is between the thermal expansion coefficient of the glass ceramic insulating layer 6 and the thermal expansion coefficient of the ferrite layer 2. It is formed by applying at a position where the ferrite layer 2 on the glass ceramic green sheet is placed by a printing method, a gravure printing method or the like, and firing at the same time as the glass ceramic green sheet.

Incidentally, the ferrite powder of the insulating layer 4 is similar to the ferrite powder of the ferrite layers 2, _Fe 2 _{O 3} of 63-73% by weight as a sintering body, 5 to 10 wt% of CuO, 5 to 12 weight NiO %, And ferrite containing 10 to 23% by weight of ZnO as a main component can be used.

The glass powder of the insulating layer 4 may be the same as the glass ceramic of the glass ceramic insulating layer 6, for example, _SiO 2 _-B 2 _{O 3 based, SiO 2 -B 2 O 3 -Al} 2 O 3 System, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system (where M represents Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O—M ² O System (provided that M ¹ and M ² are the same or different and represent Ca, Sr, Mg, Ba or Zn), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ¹ O—M ² O system (provided that , M ¹ and M ² are the same as described above), SiO ₂ —B ₂ O ₃ —M ³ ₂ O system (where M ³ represents Li, Na or K), SiO ₂ —B ₂ O ₃ — Al ₂ O ₃ -M ³ ₂ O system (where M ³ is the same as above) Pb glass, Bi glass, etc. can be used.

  The sintered metal layer 5 as an intervening layer is formed between the ferrite layer 2 covering the upper and lower surfaces of the wiring conductor 3 and the glass ceramic insulating layer 6, and includes Cu, Ag, Au, Pt, Ag—Pd alloy and A metal paste prepared by blending a glass powder with a metal powder of at least one metal of an Ag-Pt alloy and kneading an appropriate organic binder and solvent is obtained by a conventionally known screen printing method or gravure printing method. It is formed by applying the ferrite layer 2 on the glass ceramic green sheet at a position where it is placed and firing it at the same time as the glass ceramic green sheet.

The glass powder contained in the sintered metal layer 5 may be the same as the glass ceramic of the glass ceramic insulating layer 6, for example, _SiO 2 _-B 2 _{O 3 based,} SiO 2 _-B 2 _{O 3} - Al ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system (where M represents Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O -M ² O system (where, ^{M 1} and ^{M 2} indicate Ca, Sr, Mg, Ba, or Zn same or _{different), SiO 2 -B 2 O 3} -Al 2 O 3 -M 1 O-M 2 O system (provided that M ¹ and M ² are the same as above), SiO ₂ —B ₂ O ₃ —M ³ ₂ O system (provided that M ³ represents Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ³ ₂ O system (where M ³ is Pb glass, Bi glass and the like can be used.

  The sintered metal layer 5 may have the same composition as the wiring conductor 3, and a part of the wiring conductor 3 may be used as the sintered metal layer 5.

  When the insulating layer 4 is formed by combining the insulating layer 4 and the sintered metal layer 5, they are arranged side by side in the same layer (interlayer) between the glass ceramic insulating layer 6 and the ferrite layer 2 as shown in FIG. There are a configuration in which the glass ceramic insulating layer 6 and the ferrite layer 2 are laminated and a configuration in which these configurations are combined. In each of these configurations, the insulating paste and the metal paste produced by the above method are separately applied to the position where the ferrite layer 2 on the glass ceramic green sheet is formed by a conventionally known screen printing method or gravure printing method. And is fired simultaneously with the glass ceramic green sheet.

  When the intervening layer combining the insulating layer 4 and the sintered metal layer 5 is arranged side by side in the same layer between the glass ceramic insulating layer 6 and the ferrite layer 2, between the glass ceramic insulating layer 6 and the ferrite layer 2, The wiring conductor 3 can be formed using the insulating layer 4 that is an insulator and the sintered metal layer 5 that is a conductor. When the intervening layer formed by laminating the insulating layer 4 and the sintered metal layer 5 is formed between the glass ceramic insulating layer 6 and the ferrite layer 2, the stress relaxation effect of the insulating layer 4 and the sintered metal layer 5 is more effective. It gets even higher. Further, an intervening layer obtained by combining a configuration in which the insulating layer 4 and the sintered metal layer 5 are arranged in the same layer and a configuration in which the insulating layer 4 and the sintered metal layer 5 are laminated is combined with the glass ceramic insulating layer 6. When formed between the ferrite layers 2, the effects of the two configurations can be obtained together.

The ferrite layer 2 is formed together with the wiring conductor 3 on the inner layer of the insulating base 1 so as to cover the upper and lower surfaces of the wiring conductor 3. This ferrite layer 2 contains 63 to 73 wt% of Fe ₂ O ₃ as a sintered body, 5 to 10 wt% of CuO, 5 to 12 wt% of NiO, and 10 to 23 wt% of ZnO. It is necessary to obtain a sufficiently high permeability in a high frequency band that can be fired at a low temperature.

Fe ₂ O ₃ is a basic component of ferrite. If the main component of the ferrite is a solid solution having an inverted spinel structure represented as X—Fe ₂ O ₄ (X is Cu, Ni, Zn, etc.), 63 to 73 It must constitute weight percent. When it is less than 63% by weight, sufficient magnetic permeability cannot be obtained. On the other hand, when the amount is more than 73% by weight, the mechanical strength is lowered due to a decrease in the sintered density.

CuO must constitute 5 to 10% by weight of the main component of ferrite. This is because CuO greatly contributes to lowering the sintering temperature, and CuO uses the effect of promoting sintering by forming a liquid layer at a low temperature, so that the firing temperature of glass ceramics is not impaired without damaging the magnetic properties. It is for baking at 800-1000 degreeC which is. When the content is less than 5% by weight, the sintering density becomes insufficient and the mechanical strength becomes insufficient when firing is performed in the low temperature range targeted by the present invention. On the other hand, when the amount is more than 10% by weight, the ratio of CuFe ₂ O ₄ having a low magnetic property is increased, so that the magnetic property is impaired.

NiO is contained in order to ensure the magnetic permeability of the ferrite in the high frequency range. NiFe ₂ O ₄ does not cause the attenuation of the magnetic permeability due to resonance up to the high frequency range, and can maintain the magnetic permeability in the high frequency range at a relatively high value. If it is less than%, the magnetic permeability in a high frequency range of 10 MHz or more is lowered. If it is more than 12% by weight, the ratio of NiFe ₂ O ₄ is increased, so that the initial magnetic permeability is lowered. Therefore, the content in the main component of ferrite is limited to 5 to 12% by weight.

  ZnO is an important element for improving the magnetic permeability of ferrite. If the ferrite main component is less than 10% by weight, a problem of insufficient magnetic properties occurs. Deteriorate.

  The ferrite layer 2 is formed by first mixing a ferrite powder with a suitable organic binder, plasticizer, organic solvent, etc. to obtain a slurry, and then producing a ferrite green sheet by a doctor blade method, a rolling method, a calender roll method, or the like. . Next, the ferrite green sheet is cut into the same shape as the glass ceramic green sheet in plan view so as to cover the predetermined wiring conductor 3, and the wiring conductor 3 is interposed in the glass ceramic green sheet laminate. The conductor pattern is arranged and laminated so as to cover the upper and lower surfaces of the wiring conductor 3.

  At this time, in order to effectively increase the inductance of the coil conductor, it is necessary to completely cover the upper and lower surfaces of the wiring conductor 3 with the ferrite layer 2. Therefore, in order to form such a wiring conductor 3 and a ferrite layer 2, a ferrite green sheet to be the lower ferrite layer 2 on the surface of a predetermined glass ceramic green sheet, a pattern of a conductor paste to be the wiring conductor 3, Each layer may be arranged and laminated in the order of the ferrite green sheet to be the upper ferrite layer 2.

  The ferrite powder used to form the ferrite green sheet used as the ferrite layer 2 is a calcined ferrite powder, an average particle diameter in the range of 0.1 μm to 0.9 μm, and a particle having a nearly spherical shape Is good. This is because if the average particle size is smaller than 0.1 μm, it is difficult to uniformly disperse the ferrite powder in the production of the ferrite green sheet, and if the average particle size is larger than 0.9 μm, the sintering temperature of the ferrite becomes high. In addition, a uniform sintered state can be obtained because the particle size is uniform and close to a spherical shape.For example, when a small particle size is present partially in ferrite powder, the growth of crystal grains only in that portion decreases, The magnetic permeability of the ferrite layer 2 obtained after sintering tends to be difficult to stabilize.

The protective layer 7 is formed so as to completely cover from the end face where the ferrite layer 2 of the glass ceramic substrate is exposed to the end face where the intervening layer is exposed . For example, a member such as glass, glass ceramics, resin, or the like that does not penetrate moisture is used. Use it. The protective layer 7 may be formed by firing at the same time as the insulating substrate 1 or may be formed after the insulating substrate 1 is fired.

When glass is used for the protective layer 7 and formed simultaneously with the insulating substrate 1, for example, a glass powder, an organic binder, a plasticizer, an organic solvent, etc. are mixed to obtain a paste, and the glass ceramic insulating layer is added to the paste. A glass ceramic substrate composed of an insulating substrate 1, 6 having a ferrite layer 2 and an intervening layer is immersed in the paste or applied to the end face by printing or spraying, and then fired simultaneously with the glass ceramic green sheet. The

On the other hand, when the protective layer 7 made of glass is formed after the insulating substrate 1 is fired, in particular, a glass ceramic green sheet serving as a mother substrate is provided with a dividing groove, and a plurality of sheets are laminated and sintered to form a glass ceramic. It is effective in manufacturing in a so-called multi-cavity form in which each product is obtained by dividing into a sintered groove and then divided into divided grooves. In this case, the glass-ceramic green sheets and the ferrite green sheet and the insulating paste and / or metal paste multiple product layers to obtain a mother substrate was fired at a temperature of 800 to 1000 ° C. at or in a humidified atmosphere of nitrogen atmosphere The protective layer 7 can be formed by applying a paste to be the protective layer 7 to the end faces of the individual products obtained by dividing the product by the same method as described above and then baking again.

  When the protective layer 7 made of glass is formed after firing as in the above-described multi-cavity form, the characteristic change due to oversintering of the glass ceramic insulating layer 6 and the ferrite layer 2 by lowering the refiring temperature. From the viewpoint of suppressing the diffusion of the wiring conductor 3 and the like, it is preferable to use a glass having a softening point equal to or lower than the firing temperature, and it is particularly preferable to use a glass having a softening point equal to or lower than 600 ° C.

As a glass powder having such a softening point below the firing temperature, a PbO—SiO ₂ —B ₂ O ₃ system, a Bi ₂ O ₃ —SiO ₂ —B ₂ O ₃ system, a ZnO—SiO ₂ —B ₂ O ₃ system, For example, SiO ₂ —B ₂ O ₃ glass can be used.

Further, as the glass powder used in the protective layer _7, SiO 2 _-B 2 _{O 3 based, SiO 2 -B 2 O 3 -Al} 2 O 3 _{system, SiO 2 -Al 2 O 3,} PbO-SiO 2 - Even when the protective layer 7 is formed at the same time as the insulating substrate 1 when the B ₂ O ₃ system, Bi ₂ O ₃ —SiO ₂ —B ₂ O ₃ system and ZnO—SiO ₂ —B ₂ O ₃ system glass are used, Even when the protective layer 7 is formed by refiring after firing the insulating substrate 1, the protective layer 7 and the glass ceramic insulating layer 6 can be firmly bonded. Further, the glass ceramic substrate is not cracked or the protective layer 7 is not peeled off due to the temperature difference, and the end portion of the intervening layer is exposed from the portion where the end portion of the ferrite layer 2 on the side surface of the glass ceramic substrate is exposed. It can coat | cover with sufficient adhesiveness over the site | part which has.

  In the case of using glass ceramics for the protective layer 7, the same glass and filler as those of the glass ceramic insulating layer 6 can be used, and can be formed before or after firing in the same manner as the protective layer 7 made of glass. . In particular, when the protective layer 7 is formed at the same time as the insulating substrate 1, the protective layer 7 contains a filler in the same manner as the glass ceramic insulating layer 6, so that the sintering behavior is similar to that of the insulating substrate 1, and the protective layer 7 is protected. The layer 7 and the glass ceramic insulating layer 6 can be firmly bonded.

Furthermore, if the glass ceramic of the protective layer 7 is made of the same glass and filler as the glass ceramic insulating layer 6, the sintering behavior of the protective layer 7 and the insulating substrate 1 can be matched, so that the bonding can be made even stronger. The glass ceramic substrate is not cracked and the protective layer 7 is not peeled off, and adheres from the exposed portion of the ferrite layer 2 on the side surface of the glass ceramic substrate to the exposed portion of the intervening layer. It can coat | cover with good property and can prevent water absorption more effectively.

  In the protective layer 7 made of glass ceramics, it is preferable to use the same glass powder as the protective layer 7 made of glass because the same action and effect can be obtained.

  When a resin is used for the protective layer 7, it is effective when the protective layer 7 is formed after the insulating substrate 1 is sintered in the above-described multi-cavity manufacturing process, and an epoxy resin, an acrylic resin, or a silicon resin is effective. Resins, fluorine resins, and the like can be used.

In order to form the protective layer 7 with a resin, the resin before curing is applied to the insulating substrate 1 by screen printing or the like so as to completely cover the end surface of the glass ceramic substrate where the ferrite layer 2 is exposed to the end surface where the intervening layer is exposed. The technique of doing can be used.

When the protective layer 7 is formed of a resin after the insulating substrate 1 is baked, the temperature of the heat treatment (curing treatment) for bonding the insulating substrate 1 and the resin can be lowered to 150 ° C. or lower. It is possible to prevent the glass ceramic substrate from warping due to oversintering, or the occurrence of problems such as deterioration of electrical characteristics due to diffusion of the metal constituting the wiring conductor 3 or the ferrite layer 2. it can. Further, since the material is inexpensive and the protective layer 7 can be formed by using a simple device, the ferrite layer 2 having high permeability in the high frequency band without water absorption from the end face is provided. It is possible to easily provide a glass ceramic substrate in which the inductance of the coil conductor incorporated in the layer 2 is high and stable.

  In the method for producing a glass ceramic substrate of the present invention, first, a ferrite layer 2 and a wiring conductor 3 are laminated together with a plurality of glass ceramic green sheets in the manner described above to produce a glass ceramic green sheet laminate. And after removing an organic component from this glass ceramic green sheet laminated body, it bakes. The organic component is removed by heating the glass ceramic green sheet laminate in a temperature range of 100 to 800 ° C. while applying a load to the glass ceramic green sheet laminate to decompose and volatilize the organic component. Moreover, although a calcination temperature changes with glass-ceramic compositions, it is in the range of about 800-1000 degreeC normally. Firing is usually performed in the air, but when Cu is used as the conductor material of the wiring conductor 3, organic components are removed in a humidified nitrogen atmosphere at 100 to 700 ° C., and then the firing is performed in a nitrogen atmosphere.

  Further, at the time of removing the organic component and at the time of firing, in order to prevent the glass ceramic green sheet laminate from warping, it is preferable to apply a load by placing a weight on the upper surface thereof. The load due to such weight is suitably about 50 Pa to 1 MPa. When the load is less than 50 Pa, the action of suppressing the warp of the glass ceramic green sheet laminate is not sufficient. In addition, when the load exceeds 1 MPa, the weight to be used increases, so that it cannot enter the firing furnace, or even if it enters the firing furnace, the weight is so large that the heat capacity becomes insufficient and firing becomes impossible. May cause problems.

  As this weight, there is a heat-resistant porous material that does not deform or melt during firing of the glass ceramic substrate to make the load non-uniform or to prevent volatilization of decomposed organic components. Is suitable. Specifically, a refractory material such as ceramics or a high melting point metal can be used. Further, a porous weight may be placed on the upper surface of the glass ceramic green sheet laminate, and a non-porous weight may be placed thereon.

In Example 1, non-water-permeable at a portion where the end of the ferrite layer 2 on the side surface of the glass ceramic substrate using SiO ₂ —B ₂ O ₃ glass as glass and Al ₂ O ₃ as filler is exposed. The protective layer 7 was formed, and the protective layer was PbO—SiO ₂ —B ₂ O ₃ based glass.

  That is, as shown in FIG. 1, a test piece for evaluation having a shape of 5 mm × 5 mm provided with a protective layer was prepared, and the water absorption was measured. The water absorption is measured by first measuring the weight of the test piece, then immersing the test piece in water, leaving it in a vacuum for 1 hour, measuring the weight of the subsequent test piece, and calculating the weight difference before and after immersion in water. Asked. The percentage is obtained by dividing the weight difference by the initial weight, and in Table 1, it is indicated by x when the water absorption is 0.1% or more, and by ○ when it is less than 0.1%.

  The permeability was measured by preparing a ring-shaped test piece having an outer diameter of 16 mm and an inner diameter of 8 mm as shown in FIG. The permeability was measured using an impedance analyzer (“HP-4291A” manufactured by Hewlett Packard) by the high frequency current voltage method. As shown in Table 1, ○ indicates that there is no practical problem, but the permeability at 1.0 MHz and 10.0 MHz is less than 100, and ◎ indicates that the permeability at 1.0 MHz and 10.0 MHz is 100 or more. Further, the permeability characteristics are even better.

  In Example 2, the same glass ceramic substrate as in Example 1 was used, and a test piece using glass ceramics having the same composition as that of the glass ceramic substrate was produced as a protective layer, and the same evaluation as in Example 1 was performed. .

  In Example 3, a test piece using an epoxy resin as a protective layer was prepared using the same glass ceramic substrate as in Example 1, and the same evaluation as in Example 1 was performed.

In this Example 4, a ferrite containing 63 to 73% by weight of Fe ₂ O ₃ , 5 to 10% by weight of CuO, 5 to 12% by weight of NiO, and 10 to 23% by weight of ZnO in Example 1. A test piece provided with a layer was produced and evaluated in the same manner as in Example 1.

In Example 5 , a ring-shaped test piece having an outer diameter of 16 mm and an inner diameter of 8 mm was produced by interposing the insulating layer 4 between the ferrite layer and the glass ceramic insulating layer of Example 4, and the magnetic permeability was measured. .

The insulating paste for forming the insulating layer 4 is the same as the glass powder contained in the glass ceramic, and is contained in the ferrite green sheet, 30% by mass of SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder. 70% by mass of ferrite powder composed of a crystal phase of ZnFe ₂ O ₄ , CuFe ₂ O ₄ , FeFe ₂ O ₄ , and NiFe ₂ O ₄ having the same average particle diameter of 0.5 to 0.7 μm as that of the calcined ferrite powder is used. A predetermined amount of ethylcellulose-based resin and terpineol were added and mixed to prepare an appropriate viscosity with three rolls.

  First, a predetermined number of glass ceramic green sheets were overlapped, and an insulating paste layer was applied over the entire surface and dried. Thereafter, a ferrite green sheet was superposed on the dried insulating paste layer, and further, the insulating paste layer was applied over the entire surface and dried. Thereafter, a predetermined number of glass ceramic green sheets were superposed on the dried insulating paste layer and pressure-bonded at a temperature of 55 ° C. and a pressure of 20 MPa to obtain a glass ceramic laminate.

  The obtained glass ceramic laminate was placed on an alumina ceramic setter, and a weight composed of the same components as the alumina ceramic setter was placed on the glass ceramic laminate, and a load of about 0.5 MPa was applied at 500 ° C. in the atmosphere. After removing the organic components by heating for 2 hours, it was fired at 900 ° C. for 2 hours in the air.

  Table 2 shows the results of measuring the magnetic permeability of the obtained glass ceramic substrate of Example 5.

Instead of the insulating layer of Example 5, a paste containing 80% by mass of Ag powder (average particle size 1.0 μm) and 20% by mass of SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder was used. A test piece of Example 6 was produced in the same manner as Example 3 except that the sintered metal layer was formed. Table 2 shows the results of measuring the magnetic permeability of the obtained glass ceramic substrate.

In addition to the insulating layer of Example 5, a paste containing 80% by mass of Ag powder (average particle size 1.0 μm) and 20% by mass of SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder. A test piece of Example 7 was produced in the same manner as Example 3 except that the sintered metal layer was used. Table 2 shows the results of measuring the magnetic permeability of the obtained glass ceramic substrate.

Comparative Example 1

In Comparative Example 1, no protective layer was provided in Example 1.

  From Table 1, in the case of the comparative example 1 which does not provide a protective layer, although the water absorption was 0.1% or more, in Examples 1-7 which provided the protective layer, the water absorption was less than 0.1%. there were.

In the configuration of Example 4-7, the _Fe 2 _{O 3 63~73} wt%, a CuO 5 to 10 wt%, the NiO 5 to 12 wt%, the ferrite layer containing ZnO 10 to 23 wt% and As a result, the magnetic permeability became 100 or more, and the magnetic permeability further increased.

  From Table 2, the magnetic permeability of Examples 5-7 in which at least one of the insulating layer and the sintered metal layer is interposed between the ferrite layer and the glass ceramic insulating layer is compared with the magnetic permeability in the case of Example 4. it was high. This is because at least one of the insulating layer and the sintered metal layer reduces the magnetostriction acting on the ferrite layer by relaxing the stress acting between the ferrite layer and the glass ceramic insulating layer.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the gist of the present invention. For example, although Ag is used for the wiring conductor in the above-described embodiment, Cu, Au, Ag—Pd alloy or the like may be used for the wiring conductor 3.

It is sectional drawing which shows an example of embodiment of the glass ceramic substrate of this invention. It is sectional drawing which shows the test piece for measuring the magnetic permeability of the glass ceramic substrate of this invention.

Explanation of symbols

1: Insulating substrate 2: Ferrite layer 3: Wiring conductor 4: Insulating layer 5: Sintered metal layer 6: Glass ceramic insulating layer 7: Protective layer

Claims (9)

A ferrite layer having the same size as that of the glass ceramic insulating layer is formed on an inner layer of an insulating substrate formed by laminating a plurality of glass ceramic insulating layers made of glass and filler via an intervening layer. Is a glass ceramic substrate in which a coil conductor is embedded, from the exposed portion of the ferrite layer on the side surface of the glass ceramic substrate to the exposed portion of the intervening layer. A glass-ceramic substrate, wherein a water-impermeable protective layer is formed. The protective _layer, SiO 2 _-B 2 _{O 3} based _{glass, SiO 2 -B 2 O 3 -Al} 2 O 3 based _glass, SiO 2 _-Al 2 _{O 3 system, PbO-SiO 2 -B 2 O} 3 based glass _2. The glass ceramic substrate according to claim 1, comprising at least one of Bi ₂ O ₃ —SiO ₂ —B ₂ O ₃ based glass and ZnO—SiO ₂ —B ₂ O ₃ based glass.   2. The glass ceramic substrate according to claim 1, wherein the protective layer is made of the same glass as the glass ceramic insulating layer and glass ceramic made of the filler.   The glass ceramic substrate according to claim 1, wherein the protective layer is made of at least one resin selected from an epoxy resin, an acrylic resin, a silicon resin, and a fluorine resin. Claim wherein the ferrite layer, the _Fe 2 _{O 3 63~73} wt%, a CuO 5 to 10 wt%, the NiO 5 to 12% by weight, characterized by containing the ZnO 10 to 23 wt% The glass ceramic substrate according to any one of claims 1 to 4. Before SL intervening layer, an insulating layer having a thermal expansion coefficient between the thermal expansion coefficient of the ferrite layer and the thermal expansion coefficient of the glass-ceramic insulating layers with contains the same ingredients as the glass and the ferrite layer The glass ceramic substrate according to any one of claims 1 to 4, wherein the glass ceramic substrate is provided. Before SL intervening layer, characterized Cu, Ag, Au, Pt, in that it consists of a sintered metal layer containing at least one metal and glass of the Ag-Pd alloy and Ag-Pt alloy The glass ceramic substrate according to any one of claims 1 to 4.   The intervening layer contains the same components as glass and the ferrite layer, and has an insulating layer having a thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer, Cu 2. A sintered metal layer containing glass and at least one metal selected from the group consisting of Ag, Au, Pt, Ag—Pd alloy, and Ag—Pt alloy. The glass-ceramic board | substrate in any one of thru | or 4.   The intervening layer contains the same components as glass and the ferrite layer, and has an insulating layer having a thermal expansion coefficient between the thermal expansion coefficient of the glass ceramic insulating layer and the thermal expansion coefficient of the ferrite layer, Cu , Ag, Au, Pt, an Ag—Pd alloy, and an Ag—Pt alloy, and a sintered metal layer containing glass and a sintered metal layer formed so as to be aligned in the same layer. The glass ceramic substrate according to any one of claims 1 to 4, wherein:

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